Let us take this one by one.
3 ch sts, turn, 1 t c into the last st of each row to the top, 3 ch sts, turn. 1 t c into each t c, omit using the 3 ch sts as a foundation for the t c;
What this is telling you is to work on the edge of each row. (This next part is up to you. What I would do is place back on yours and have someone measure to see where to start the sleeve.)Break yarn and attach at that point. This next part, omit using the 3 ch sts as a foundation for the t c; is telling you to decrease, by not workong a stitch in the turning chain.
I hope this helps. let me know. gin48k@gmail.com