You will need to spend at least $5.00 USD within the Steam store.
Some examples of purchases that grant access to these features are:
Adding the equivalent of $5 USD or more to your Steam Wallet
Purchasing game(s) that are equal to $5 USD or more from the Steam store
Adding a Steam Wallet card that is equal to $5 USD or more to your Steam account
Purchasing a Steam gift that is equal to $5 USD or more from the Steam store (Receiving a Steam gift from a friend doesn't count)
Each Steam purchase total will be tracked in USD. If your Steam store's currency isn't in USD, it will be tracked and converted to USD automatically using daily exchange rates.