Trying to get started

I rode the bike Tuesday for 20 miles.  I was restless for the first 5 miles or so.  I settled in after that.  I did take a couple of short breaks to grab some water.

I went to cardio kickboxing Wednesday night and my inner thighs were killing me by Thursday night.  I tried to ride Thursday night, but only rode 8 miles.  I stopped 3 times to stretch my legs.

I'm not sure how to get this whole training thing started.  I've been trying to find some sort of schedule on the internet.  Something to help me figure out what my weekly goals should be.  I have found some information, but no luck in finding an actual training schedule for a 300 mile tour.  I did find one for a 100 mile ride.  I'll keep looking and in the mean time I'll ride as much as I can.