SloppY and Logan15xx,
Now is a good time during your Junior year to send letters to baseball coaches.
Go to a sight such as
US Universities by State find the schools that interest you, click on them to go to their website, go to baseball, then to Coaches to get the name of the coach. Most websites will have a mailing address and an email address in which you can contact the coach. While you are at the website, check out their baseball program and look at their roster to see how many players they already have that play your position. Lots of information on their websites.
The sample letter of introduction on the High School Baseball Web is a good one to go by. Basically, you just want to introduce yourself to the coach, tell him somethings about you (baseball and academics) and let him know that you are interested in playing in his program.
Get started right away, and good luck!