Deprecated, unless you guys want an update, this cannot be used as reliable information.

Alrighty! lets get started

Step 1: go to this folder C:\Program Files (x86)\Steam\steamapps\common\Besiege
(this is where it normally is, if you've installed through steam.

Step 1: go to this webpage http://forum.spiderlinggames.co.uk/forum/main-forum/besiege-early-access/modding/8432-spaar-s-mod-loader-1-0-1-besiege-v0-2
Step 2: Download Spaar's mod loader, NOT INSTALLER!!!! (very important) The installer is very experimental, and doesn't always work.

Step 3: go to Besiege_Data in your folder explorer

Step 4: See where it says managed? open that folder and plop the Assembly-Unity something or other in there, and when it asks, replace file.

Step 5: Go back a file and create a new folder and call it Mods, now, inside of that drop EVERYTHING else in that folder, except for readmes and such.

Step 6: Congrats, you have now installed a modloader! to install more mods, just place them in your mods folder!

Step 7: now, go download those mods of your dreams!

Step 8: get a mod called Multimod; it is really useful!

Step 9: to get Blockloader, drop the Blocks folder in your mods folder, and the Blockloader.dll into the mods folder, and done!

Like and comment if you enjoy, and/or want more guides from me!

Sadly, there is no mod menu that will keep your mods up-to-date, so you will:

1. Have to scourge the mod forums to look for the mods you want. (Or I can create a list here, if you would like)
2. Have to, every time there is a new update, get the latest version of Spaar's, and all the other mods, as they will be incompatable.

I hope this helps!