Hey welcome to CC!
Of course you can colour fondant yourself 
It is best to use paste or gel colours to colour it so it doesn't go sticky and all you need to do is put some colour on your fondant with a toothpick a little at a time (if you want to get a dark colour you can put a little more at a time) and knead it into the fondant and keep doing so until the colour has dispersed properly and is nice and even (unless to want a streaky look or want multiple colours on your fondant not mixed together too much).
However if you are using one colour for your one batch of fondant you can add the colour into your fondant mixture while you are making it eg. I make marshmallow fondant so sometimes i will add the colour to the melted marshmallows.
HTH
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