To start, I recommend trying to learn one song that interests you and go from there. Shivers, Flex and The Wolf are great and popular beginner line dances. It's okay if you make mistakes too, it's most important to have fun. To help learn how line dances are done, I recommend reading below.
Line dances are made up of repeating "counts", commonly being 16, 32, 48, and 64 counts (can be even more!). These are made up of steps, such as the Wizard step, Coaster step, Sailor step, and Grapevine. After learning a few and doing lessons, you will likely soon start to piece them together and recognize them in other line dances.
Counting "beats" on counts goes in sections of 8, being "one, two, three, four, ... seven, eight". It also can use "and" in between, like "one and two and ... seven and eight and". Counts help keep track of timing with the stepsheet (aka the dance's choreography, copperknob.co.uk is great for stepsheets).
Line dances are made up of "walls", being 2 or 4 wall line dances. You may often hear the 3, 6, 9, and 12 o' clock walls, being like the numbers on a clock. These signal where to face following the moves and where it restarts or has a tag (more below).
"Tags" and "restarts" are the last part to line dances. Tags are parts of the song where short sets of steps are added, often changing to the music. Restarts are when the dance starts again at a unique spot. Not all line dances have them, but knowing the ones that do beforehand can be helpful.