First, we need to clarify what is a CSGO marketplace. It is a community where you can buy and sell different so-called skins for Counter-Strike Global Offensive. What is Counter-Strike? It is an online computer game with a huge network of players. What are skins? Skins can be called finishes as well, and they were recently introduced to the game with the Arms Deal update. They are basically weapons which can be used in the game, but they hold no function, they are simply design elements.
There are multiple ways to earn or purchase these skins. You can earn them during random drops, with opening containers or they can be traded with other traders on the Steam Community Market, more commonly referred as the Steam Market.
The steam market is a marketplace where you can purchase and sell in-game features, these so-called skins, and other items. You need to be registered on Steam and have a Steam Wallet, and you can start trading. By the way, the Steam Community is much more than just trading items for Counter Strikes. It has endless numbers of games, by joining Steam you have instant access to thousands of games, you can share a lot of content with your fellow gamers, you can set up a conversation about different topics, you can use steam on several devices as well (PC, Linux, Mac, mobile or even you TV).
The more games you play on Steam, the more so-called virtual Steam Cards you are going to earn, and then later you can trade or turn them into different badges and different Steam Community Items. For CSGO, you can buy real csgo knives on Csgotradezone.
But how do I actually buy and sell on Steam Market?
Well, you have to create an account on Steam first. With this account, you are going to get a Steam Wallet where you need to transfer funds if you would like to buy items from other gamers. Once you created your account, you log in and click on your username. There you select account details and `add funds to your steam wallet`, you choose the correct amount and proceed to checkout. You can add funds to your wallet by purchasing Steam Wallet Cards which are actual, physical cards which are accessible depending on your location. Just go to Steam website and check where is the nearest shop around your place. You can also purchase codes via SMS or text and can be put on your wallet. Probably the easiest way to do it though is through your PayPal account directly.
When you already have money in your wallet, you can start buying and selling. It is quite straightforward. So, you are logged-in to your account, in the left-hand corner you choose the Community button and then select the Market (so that you know you have to have the game for more than 30 days in order to be able to use this function). Then you can click Search or Advanced options and a bunch of filters will come up and you can click the ones you want to include in your search. Click on Search again, and the list of the items will come up on your screen with the prices shown next to them. From here you just click and bid and buy.