right-click

Use only when you need to talk specifically about mouse actions. Define in content that teaches beginning skills if you think it's necessary.

Use select and hold (or right-click) when the instruction isn't specific to the mouse.

Hyphenate.

Examples
Right-click to select the file.
Using the right mouse button (right-click) ….
Select and hold (or right-click) the Windows taskbar, and then select Cascade windows.

See Describing interactions with UI, Mouse and mouse interaction term collection