If you want to specify the amount to receive, go to the 'Merchant' page (after you selected in the 'Receive' page the @account that will be used to receive XMR).
Insert the amount to receive, then share with the payer the payment URL or the QR code. If you want to track the payment in real time, tick the 'enable sales tracker' option.
Wait until the payment has arrived and has enough confirmations (The more confirmations, the safer the transaction is. You need at least 10 confirmations before you can spend the funds.).
If you prefer to not directly deal with the wallets, you can use a third party payment system. Members of the Monero community have created a set of integrations for various platforms and languages. You can find more info on
If you are a business and you wish to programmatically receive @transactions or use advanced features like multisignature, it's suggested to consult the
If you need support, the community will always be happy to help. Come chat on #monero, the chatroom is on Freenode, but also relayed on MatterMost and Matrix.
Some of those offer nice features like the possibility to automatically convert part of your income in fiat money or to accept other cryptocurrencies along with Monero.