How to connection 20 ft of strips?

I am new so go easy on me

I want to use 20 continuous ft of light strips. I purchased 2, 10 ft strips thinking I can connect them. I saw a few videos and diagrams. But I’m having trouble figure it out. I was hoping they’d have a 10 ft extension without the base but they don’t. I only saw 3ft. If I can connect them, any tips for what I should do with the second control box?

Thanks!