Hi Holly,
To get started all you need to do is show up at the Episcopal Church home you've found. If you've not yet found a church near you that you like, a little investigation using the web and visiting once or twice can really help you decide if the community is one that you like. You probably know that there is some controversy in the church right now...most congregations tend to be broad or progressive, but there are also some that are quite conservative by comparison. You may find one or another that suites you better.
If you've been baptized in pretty much any Christian church you can take communion at any Episcopal Church. This is a good time of year to get involved in the church because Lent is a traditional time for programs that aim toward confirmation in the church (you don't have to be confirmed to become a member though). Such programs would give you a good introduction to Episcopal worship. A defining aspect of the Episcopal Church is that we are unified by our worship, which means we have a lot more room for a variety of doctrinal teachings.
If no courses are being offered at the church you find, there may be an adult Sunday School you could attend, and of course you should feel free to talk directly to the priest to ask all of your questions about the Episcopal Church. As I said, the best thing to do is just start attending, talk to the people there, and if you so choose eventually you can be confirmed into the church to make it more 'official.' That last step however is not a requirement for being part of the church.
Please feel free to ask if you have any other questions.
luna