How to create writable lines in Word that continue after the text goes to the next line?

I know EXACTLY what you're trying to do and I'm having the same issue.  The only thing that I've found works, but it is a little tedious.  Type a few words on a line and just copy paste how ever many lines that you need or want to create.  Be sure and type full lines that go all the way across the page.

Then, go to the "Insert" tab & select "Shapes" & "Line."  Choose the 1st line (straight line) and draw a line under your text (hold down the shift key while drawing to make a straight line).  The line automatically comes up blue but while the draw tool was open I clicked and changed mine to black.  You can then repeat this step for however many lines you typed or while that line is selected, just copy & past that same line (which is what I did).  If you copy & paste you just have to realign the line under your text.

Next, go to the end of your text and hit the backspace key until all of the text is removed, your lines will stay in tact.  If you just select all the text and hit delete, for some reason this screws up everything so backspace is the way to go here.  After all your "made up" text is deleted, just start typing and you will see that your text comes up on the line and it automatically goes to the next line and continues.  No need to hit enter or tab, it automatically wraps to the next line.  I should note something interesting I found in doing this, when you're hitting backspace & deleting text, it appears at times to create a double line or thick line when you're hitting backspace.  DON'T PANIC, once you start typing the lines will appear normal AND it will give you an extra line to type on also.  Example, if you create 3 lines, when you get to the end of the 3rd line, a 4th line will just appear for you to type on.  It only gives you the one line though.  If you continue typing after that, the extra line just continues to drop.  I really hope you find this helpful and I wish Microsoft would make this easier for their users.

I find the easiest way to create such lines is with a border. The paragraph border you were generating by typing several underlines and pressing Enter (creating by the AutoFormat As You Type setting for Automatic Borders) is a Bottom Border. If you instead apply a Inside Horizontal Border, then it will be applied to every paragraph, so every time you press Enter, you'll get a new line. You can control the spacing of the lines with the paragraph line spacing, Spacing Before/After, or font size.

To apply an Inside Horizontal Border, create at least two empty paragraphs and select them. On the Home tab, in the Paragraph group, click the arrow next to the Borders button and select Inside Horizontal Border. You'll also need to apply a Bottom Border to the last paragraph.

Note that these are printable lines, but you will not be able to type on them in Word with normal word wrap at the end of a line. The only way to get such lines in Word is to use drawing lines, spaced as required and formatted as Behind Text (see http://word.mvps.org/FAQs/TblsFldsFms/LinesInForms.htm).

I meant straight underlines on which it is possible to write on within Word, without the need to stop writing before the end of each line and continue on the next line by clicking on the next line each time.

I do not need any checkmarks or anything else, just straight horizontal lines on which I could write on and when the text reaches the end of the underlined line it goes automatically to the next line which would be automatically underlined as well OR that I can create the underlined lines myself, but at least the text would go automatically onto each next underlined line when it reaches the end of the previous one.

Example: I create 3 consecutive straight underlines by using --- + enter. When I write my text on the first underlined line and it reaches the end of the line, the continued text goes automatically onto the next line, but with that it just pushes the first underlined line one line lower which is what I want to avoid.

Any help would be appreciated!

What you mean writable lines in it?

For writable fill form check this:

http://office.microsoft.com/en-us/word-help/create-a-fillable-form-HA102840128.aspx

With drawing lines you can fill a page with lines that the text, as you create it, will sit on; the text will wrap naturally to the next line. But you can't have the lines magically appear as you type, if that's what you're asking.