Here’s a very informative post by WhoBloxedWho on how to create a basic IK Solver for foot placement. Please note that he adds a few things later on in the thread - give them a read as they could be important to you.
Also in the future please remember to follow the guidelines for this category on how to create a post for support, as well as use the search feature on the forum to see if a similar question to your’s has already been answered.