You have to guru the radical lessons before you can access the kanji lessons. To guru the radical lessons, you have to review them and get them right several times.
Did you look at the FAQ? Unofficial FAQ
Q: I’m level 1, why do I need to wait so long for my reviews? I am only reviewing radicals, when do I get kanji?
A: Good question. WaniKani uses a system known as Spaced repetition. You can read more about the specifics of the SRS (spaced repetition system) algorithm used here in the WaniKani guide .
Here is a brief summary of the info in the guide: To unlock kanji, you must first “guru” all component radicals. To guru a radical means that you answer it correctly in a review after a two day SRS interval (this is what your level 1 radical review intervals will be: 2 hours, 4 hours, 8 hours, 23 hours). So it takes a while (minimum 37 hours) to see your first kanji! Eventually, once you start to guru kanji, you will begin to unlock vocabulary as well. Everything on WaniKani builds on previous things you have learned, so your reviews will ramp up dramatically as you level.