The question may be very simple, but I still don't know how. Thanks.
You can use the search feature to turn up questions where more than one tag is applied:
Then sort the results to your liking. However, there's no
or operator that I know of. In other words, searching
[php][lisp] isn't going to show you PHP or LISP questions, but questions tagged php and lisp. That may change, as Stack Exchange is investing a lot of time and talent into the functionality and features of the search.
However, both the front page and the questions page should be a rather nice blend of questions that are marked with some of your favorite tags. For now, I think that's the best you can find.
Under questions, on the right navigation bar click on your favourite tag and there you go. Or search for tags and only those questions will come up
I think you cannot have multiple tags active at the same time. when you choose a tag only the questions related to that particular tag will be displayed.