How to store customer input in a liquid variable?

[OliverB]

Greetings!

I'm currently struggling creating an input field for customers to type in some data on my website, to then store whatever is inputted into a variable that can then be used in other parts of the code. 

I've created the input field but I can't seem to figure out how to store whatever data is entered into it....

Any basic code with this feature would be greatly appriciated!