Re the signature:
At the top of the page, right side you will see something that says Bethkay12 profile, next to view your posts. Click on where it says profile and it will take you to a control page. The control page has a horizontal menu that says overview, profile, board preferences, etc. When the page opens up it is set on overview. Click on the profile tab/button. That page has a vertical menu that says edit profile, edit signature, edit avatar, etc. Click on edit signature and type in what you want. Be sure to save. It is actually easier to do than to describe here.
Re your mint etc: When you said the leaves are being eaten from the inside, does it look about like this:
If so, that is a leaf miner. It is not the worst pest you can have, because the plant can withstand a good bit of that without being harmed much. But you don't want to let it turn in to a major infestation. Just pull off and destroy (not compost) any leaves with marks on them. The leaf miner is the larva of some little fly or moth. When it has eaten enough of the leaf tissue to grow full sized, it will chew its way out of the leaf and drop down into the soil below. It will burrow a little into the soil, pupate, and come out as a new adult. If you keep the soil covered, with weed barrier or thick mulch so the larva can't get to the soil, it will interrupt the life cycle and help prevent the next generation.