Head up the Grand Concourse. A couple of blocks north of 149th street, the road widens a bit, Make a right on that first side street. You can only go 1 - way. On that block, there's a parking lot. I'm not sure how much it cost this year. In the past, it was $10. YMMV. If you're lucky, you may find a street spot.
It's a 10 minute walk to the stadium.
When you leave, make your first left, then left again (south) on the Concourse. You're heading back to 87 at 138th street. From here, you can head north on 87 to 95 (Cross Bronx); or, head south on 87 and follow the signs to New Haven.