To open Tubular! extract the .zip file then enter the folder once you're in the folder click the "game" folder from there click the folder corresponding to your platform click the "Tubular [the version the game you dowloaded] (Open me in FireFox).html" and open it in a browser any browser that supports html5 should work however the game was created with FireFox in mind so you may run into bugs that may not happen while using FireFox, once you're in the game look to the top left of your screen then hover over the script button, while your mouse is on the script icon click the "1" key, once you've done that locate "testinggrounds.pms" now click the "click me" button now you should have so ground to stand on!
To move your camera use the scroll wheel (if you don't have a mouse you can use the arrow keys) hold shift to scroll verticaly, you can use the [W][A][S][D] keys to move your character around and left click to punch.
Look back up at the top left corner of your screen, now hover over the profile button from there press 1 to begin profile creation you will first be prompted to chose a numbric colour (0 - 100) for your torso after that you should be asked to chose a colour for your other limbs then you should be prompted to enter the id for your hat you can find the hat ids in the Catalog rinse and repeat until it prompts you to give your self a name your name does not have to be unique after that you'll have to give yourself an id so scripts and servers can identify you this id has to be unique do not give yourself an id thats easy to guess and do not share it also make sure to write it down somewhere if you want to make changes to your profile in the future, after that you can manage your profile data by going back up to the profile button then go down to the "?profiledata" list and right clicking it.
Open up https://studio.penguinmod.com/editor.html in a new tab once you're there delete the default sprite go the "extensions" tab locate "Physics" by griffpatch, click it then make a comment in the backdrop containing the following text:
"Configuration for https://penguinmod.com/
You can move, resize, and minimize this comment, but don't edit it by hand. This comment can be deleted to remove the stored settings.
{"framerate":60,"runtimeOptions":{"maxClones":Infinity,"miscLimits":false,"fencing":false},"hq":false} // _twconfig_"
without the quotations at the beginning and end while you're there add this script to the backdrop 
then save the project to your computer and load the project from there open the testing grounds sprite from eariler inspect the code then turn it into your own.