Do not tell him you have a crush on him. Reasons are two-fold:
1. It'll boost his ego, and you'll lose your appeal to him. Guys, in general, don't like needy or clingy girls. The more independent a girl is, the more appeal she has. Women are more emotional creatures, so you tend to gravitate towards expressing yourselves. You CAN express yourself, but do not be too obvious or blatant. There are so many other ways to express your interest in him without making yourself vulnerable to the situation, and telling him you have a crush on him is one such thing. You would usually lose some stock value if you do that.
2. If he doesn't reciprocate your feelings, you'll wish you can dig a hole right then and there and stick your head in.
You just gotta know it's all a subtle game, albeit one that can be played without malice. However, things seem to be looking good for you, with him texting you and all. A lot of flirting or 'conveying your intentions' can be done subtlely by text messages if you're the shy type. Give him a lot of eye contact when you do see him, and smile a lot. Try to hold a conversation about any topic and make yourself a interesting person to be around with. And, oh, don't be worried about losing him. If you feel that way, you'll somehow look that way, and you'll give off bad vibes

Let us know how it goes. good luck.