I need help on turning off the free select tool after use on gimp.

And what tool do we use to bend lines to create a mouth.

For Gimp;

Ctrl+a - Select All
Ctrl+d - Select None

There are many tools that you can use to create a mouth. I'm definitely no expert at this but you can use the line tool to 'sketch' the mouth and then use the stroke tool. If all else fails you can just use the brush tool.

This all depends, ofcourse, on the type of mouth you are creating. I suggest checking out the tutorials on making heads.

you really have to have a steady hand to use the brush or pencil tool. which is what i use for the one head i created.. which came out nice

Do you download gimp or do you buy it?

Gimp is free. You dont need to buy it.

holding shift and making a dot also helps create a straight line