Open a channel to our node at: firstname.lastname@example.org:9735
Open with an amount that is the total amount (i.e. sum of amount you want to be able to send and receive). Then goto: LN->BTC and enter your bitcoin address and an amount. This is the amount you want to be able to receive on the Lightning channel. You will then be shown an invoice. As soon as you pay this invoice the BTC will the set to you and your channel will be able to receive funds.
If you have a channel where you have made a number of payments and it is now "empty" you can refill it without the cost of 2 transactions to close and reopen. Instead create an invoice for the amount you want to re-fill it with then goto: BTC->LN. Enter the invoice (and a return BTC address - this is just in-case the lightning payment fails). You will then be shown a BTC address to make a payment to - once this payment has 2 confirms we will forward the Lightning payment and refill your channel.