To appear offline on Steam, you can follow these steps:

Launch Steam: Open the Steam application on your computer and log in to your Steam account if you haven’t already.
Access Friends List: In the top menu bar of the Steam client, click on the “Friends & Chat” option. This will open your Friends List and the chat interface.
Set Your Status: At the top of the Friends List, you’ll see your current online status displayed next to your profile picture. Click on the dropdown arrow next to your status (it might say “Online” by default).
Choose “Invisible”: From the dropdown menu, select “Invisible.” This will set your status to appear offline to your friends, even though you are still logged into Steam.
Confirm Status Change: Once you’ve selected “Invisible,” your friends will see your status as “Offline.” You can still access and use Steam normally, but others won’t know you’re online.

Remember that while you’re in “Invisible” mode, you won’t be able to see your friends’ online statuses either, as you’re intentionally appearing offline to them. If you want to go back to your normal online status, you can simply repeat the process and select “Online” from the dropdown menu.

Please note that the specific steps might vary slightly based on any updates or changes to the Steam client’s interface, but the general process of changing your status to “Invisible” should remain similar.