Your first equation is correct for the perimeter: 2x+2y=36
The second equation requires you to translate "The length is 10 ft. longer than the width"
Using x as length and y as width, we can translate the sentence: x is 10 ft. longer than y
Generally, "is" means the "=" sign, so x = 10 ft. longer than y
and finally longer than usually translates to addition "+" or x = 10+y
To solve the two equations, I would recommend substituting the second equation's y+10 into the first equation for x, i.e. 2(y+10) + 2y = 36. I'll leave solving this for you, but feel free to email me or ask a follow-up if you do not understand this part.
Once you solve this for y (the width), you then can add 10 to y to find the length (x).