At the moment Lobstr does not provide exchange services and does not allow to deposit/withdraw fiat money or anything other than Stellar.
In order to buy or sell XLM, we recommend to use one of the trusted third party exchange services.
Some of the popular exchanges which support Stellar (XLM) are:
- Bittrex: https://bittrex.com/
- Binance: https://binance.com/
- Kraken: https://kraken.com/
- Poloniex: https://poloniex.com/
Once you have the XLM, you can transfer them to Lobstr wallet by following instructions in the Receive page: https://lobstr.co/receive/
When sending XLM to Lobstr memo is not required, because Lobstr provides unique addresses for all our users.
(If the service that you are using to send transaction requires you to specify memo - you can safely enter just "Lobstr" there.)