MySQL - Indexing questions
===

I'm for the first time making a bigger database using MySQL. Since it's going to be a bigger one I need better performance for the queries. So I looked into indexes. Since this is what I was learned I always make a column named id which is auto-incremented and is used as a primary index.

After some searching and reading I think I've understood some things about indexing but I want to be sure.

Indexes is useful when you use a select query with, for example a WHERE clause because instead of searching the whole table, it just searching in a smaller part. You should index things that are used in WHERE and JOIN clauses.

Is it good enough to just add a index in phpMyAdmin on the columns that you want to index or do I have to do something when doing a select query? 