HP Pavilion Slimline devices provide basic computing functionality in a very small package, making them well-suited for tight spaces. In general, if you wish to include wireless capability with your Slimline computer, you select that option at the time of purchase; however, if you've acquired your computer through a third party or are reconsidering your networking needs, you may be able to add wireless to your Slimline yourself.
The easiest way to add wireless capability to your HP Pavilion Slimline is through the use of a USB wireless adaptor. These devices connect to the USB ports in the front or rear panel of your computer (the exact location may vary depending on the model). Installation is very straightforward; once you install the driver software for your USB adaptor, all that remains is to plug in the device and make sure your wireless settings are properly configured. If you'd rather not use up one of your Slimline's open USB ports, one alternative is to install a PCI-e wireless card. This may prove difficult, however, as a Slimline's case is so small and often the internal components are designed specifically by HP for the purpose of fitting in the available space. Before you purchase a wireless card, you should check inside your casing to see how much room you have to work with and make a decision from there.
To open your Slimline's case, all you need is a Phillips screwdriver. But first, be sure to disconnect any cables or peripheral devices that may be connected to the computer, including the power cord. Look for the screws on the rear panel; once you remove those, the case's side panel should lift right off. Avoid handling the internal components any more than you need to, and touch a nearby metal surface beforehand in order to minimise the risk of a static discharge. One option to try if you want to install a wireless card is to remove the card's metal bracket; this bracket is used to secure the card to the computer case, but is not strictly necessary in order for the component to operate properly.
Depending on how much space you have to work with, removing this small piece may reduce the card's size by just the right amount. You may also find that you need to remove an existing card in order to free up an available slot; the modem card, if installed, is likely your best option here (although your specific needs may vary).