How can I backup internal HD to external SSD

Ok, a bit confusing but try to stay with me because I desperately need help.

I removed the internal hard drive from my late 09 iMac 27’

it is a 2 TB stock hard drive. But I only used about 250/300gbs total

I bought a Hard drive dock station and connected it to a friends macbook.

I also bought a 500 Samsung external SSD

i connected that also to the laptop.

I want to transfer all all of my data from my iMac to my SSD using my friends MacBook.

What is is the easiest way to do this ?? Somebody please tell me this is possible.