I cannot create my own coins. I keep getting an error like this "Error: Check tx error: Insufficient funds for sender account:".

The error means that you do not have enough funds to create your own coin. Most likely, you chose a short Coin Symbol (for example, BTC) as they are more expensive by default. Commissions when issuing coins:

3 characters — 1 000 000 BIPs + standard commission per transaction
4 characters – 100 000 BIPs + standard transaction commission
5 characters – 10 000 BIPs + standard transaction commission
6 characters — 1 000 BIPs + standard transaction commission
7 characters — 100 BIPs + standard transaction commission
8 characters — 10 BIPs + standard transaction commission
9-10 characters — only the standard commission for the transaction (MNT in the test network). Please also make sure that you have enough funds on your balance for a specific initial coin reserve you want to set.