I really want to massage my mom’s feet,but I don’t know how.

Offer to do one after she's had a long tiring day at work. It would be double nice if you could massage her feet while she's wearing pantyhose.
My mom's a flight attendant and I was 16 when I first started giving her foot massages. She'd been divorced from dad 3 years. Dad claimed she was gone all the time so he started hooking up with a co-worker.
It was a Friday evening, I was between girlfriends and mom would be in town for 3 days. I picked her up at the airport and she'd already had a couple of glasses of wine from a hotel bar. I could tell she was 'happy'. lol
On the ride home, she took her shoes off and reclined the seat back in my SUV and put her feet on the dash. The ride to our apartment wasn't long but I'll admit that had me rock hard! She vented a little about her last flight and some rude passengers.
We got inside, she poured another glass of wine and she sat on the couch. She was already buzzed and I've never known her to have more than two glasses. Normally mom would jump into the shower as soon as she got in but this time she asked me to sit with her. She turned sideways and put her feet on my lap. I could see up her skirt as she vented. I started massaging her feet. She enjoyed it. I was rock hard and she had to know it. I'd accentually glide one of her feet past the tent in my shorts and I'd notice her smiling at me while sipping her wine. When she finished venting and her wine, she got in the shower.
I had to take care of things myself.
From that moment on, when she came home from work. I gave her a long foot massage.