how do you do plus or minus on this

ok what do you even mean

Well, first of all to get the plus and minus onto the screen you should type it down first.

So look for it on your laptop/computer.

For me, it's on the top-right corner. And to activate the plus I hold (pause) for my laptop.

In some cases it's Ctrl or alt.

But minus, i just have to click it.

+ and -