There are only 10 possible straights, so it won't be that hard to list them here:
Ace-2-3-4-5
2-3-4-5-6
3-4-5-6-7
4-5-6-7-8
5-6-7-8-9
6-7-8-9-10
7-8-9-10-Jack
8-9-10-Jack-Queen
9-10-Jack-Queen-King
10-Jack-Queen-King-Ace
There are 3 possible ways for you to have the straight:
First, any of the 3 cards for the straight are on the board in the middle (community cards) and BOTH your cards are the other 2 that make up the straight.) Example: The board includes a 5-6-8 and you have a 7-9.
Second, any of the 4 cards for the straight are on the board in the middle (community cards) and ONE of your cards are the final one that makes up the straight.) Example: The board includes a 2-3-5-6 and you have a 4 in your hand.
Third, all 5 community cards in the middle form a straight all by themselves. (In which case everyone in the hand has made a straight.) Example: The board is showing 8-9-10-Jack-Queen
The thing to worry about in the final example is if someone has a King in their hand (or a King and an Ace), in which case their straight would be higher than other folks.