This guide is primarily intended for first time Frame and Lattice users, but you might find it useful even if you're not new to the app and you want to make sure you're doing everything right when installing Frame on a new computer or re-installing.
Frame is composed of two parts, the Frame desktop application, where hot wallets and hardware wallet connections exist, and the Frame companion browser extension that injects into dApps just like MetaMask does. It even has a compatibility mode for dApps only suited to MetaMask and can inject "as MetaMask" on these sites, even if there's no native support for Frame. Installing Frame is quite straight-forward: head over to frame.sh and download/install the correct version for your system. Also, scroll down a bit on the Frame website and click the Firefox or Chrome icon to install the Frame Companion browser extension.
Frame will appear as a system widget on the right side of your screen and can be summoned and hidden using the
option+/keyboard shortcut. The Frame companion extension allows you to quickly switch between networks and toggle the MetaMask compatibility mode.
You are not required to use a hot wallet in Frame so no further setup is necessary if you plan on only using your Lattice via Frame.