Searching multiple mysql tables, Joins?

I'm creating a mysql keyword search on my website and I know how to search a single mysql table, my problem is I need to search 15 different tables simultaneously, they also all have the same column names. I was told I have to you JOINS but i've never used them before. How is this done?

MY SQL SELECT:

SELECT *

FROM mytable1

WHERE keyword LIKE %colname% OR id  LIKE %colname%