Installing the stable diffusion web ui is straightforward. Create a directory and then download the webui.sh script. The script will pull in the repo and install everything it needs. This may take a bit.
https://github.com/AUTOMATIC1111/stable-diffusion-webui
mkdir A1111
cd A1111
wget -q https://raw.githubusercontent.com/AUTOMATIC1111/stable-diffusion-webui/master/webui.sh
chmod +x webui.sh
./webui.sh
Once everything is installed the web ui will be launched. This will be faster after the initial run.
You can get the stable diffusion model on huggingface or other models at civitai.
Models are placed in A1111/stable-diffusion-webui/models/Stable-diffusion/