Use edit
Make your own userpage like User:YourUserName/userboxes/speed and edit page and place
{{ userbox
| border-c = #4169E1
| info-fc = red
| info-c = black
| id-c = white
| id = Speed
| info = This users download speed is x kbps and upload speed is y kbps
}}
Edit x to download speed and y to upload speed