[Locke.]

I don't know if it's the same on a phone or not, but on a computer you go to a players profile that you want to choose, and there should be a drop down menu saying 'Squad' or something like that, up where you would usually have 'Transfer', 'Contract', etc.

If all 22 spots are taken you''d probably have to remove players first though.. I think to do that you'd probably have to do the same as above, but you'd have the option to remove them rather than add