If the sport of swimming just came on your radar you're probably ridiculously intimidated! If you are brand new to swimming the first thing you need to do is get in the pool for twenty to thirty minutes! Try to keep track of what you're doing and even log the total amount of distance you do! After each 25 (one length of the pool) you're allowed to give yourself a rest. If you get bored, mix in strokes, drills, and kicking. I have provided a workout below for first timers. Bring it to the pool so you can follow it!  

8x25 freestyle up, backstroke down 20 second break between each 25

6X50 Choice of stroke 30 seconds of rest

2x100   KIck with a kickboard 45 seconds of rest

50 yards (2) laps warm down

If this is too much for you it’s ok just get through what you can! You can build up to more through practice! And eventually you can push yourself when you get more confident with the distance! Also if you’ve been in the pool before but need some motivation there are masters and usually recreation classes that serve to provide workouts for adults looking to get more active in swimming.