Hi, Susan!
Welcome! These boards are an awesome place. You can feel at home really quickly.
Congrats on deciding to get back into biking. Once you get the discomfort part figured out, you'll love it!
Riding a bike on a trainer is so different from on the road....... On the road, you are moving your butt around and getting in different positions, without even thinking about it. But on a trainer, unless you consciously do the same thing, its a static position. You sit and you pedal. OUCH! After thousands of miles on my bike during the riding season, I STILL get sore after the first few sessions inside unless I remember to change positions as I ride. You can sit straight up, you can lean forward on the bars in an aero positions, but most importantly, make sure you stand up frequently. Get all the weight off those bits and pieces, off the rear end, too. Let the blood flow be restored. It only takes a matter of seconds. Stay standing longer, occasionally. It makes for a nice variation in the routine of trainer riding.
Good luck! Have fun!
annie
Time is a companion that goes with us on a journey. It reminds us to cherish each moment, because it will never come again. What we leave behind is not as important as how we have lived." Captain Jean Luc Picard