Just getting started with Bitcoin and trying to play around with all the tools to get a better feel for everything. One big step obviously is understanding how to use Cold Storage. So today I got Electrum setup on an offline computer (an old ThinkPad running Xubuntu 14.04) and the online one on a Mac running OSX 10.10.

I managed to send funds from a coinbase account (just a bit as a test amount) and it's showing on my online Electrum. I wanted to try and send it back to coinbase to try out sending funds so after the receiving transaction was approved on the online wallet I went through the process of sending from Electrum. I exported the file, moved to a USB, copied the transaction file to the desktop of the offline wallet computer but then when I wanted to load the transaction (from file) I got the error message: "Electrum was unable to parse your transaction".

As a possibly related question (maybe this is what is causing the error), how do you get received funds to show on the offline wallet? Is there someway that the two sync or is the offline wallet really just a way to sign and verify the transactions?

Sorry if these are noob questions, but I've spent all afternoon and evening trying to search for answers to these problems and haven't found anything anywhere. So hopefully there'll be some answers here as getting my cold storage up and running is my last hurdle before getting more invested in BTC. 

Thanks!