You can create a squad badge that appears on your vehicle units in game. Your squad badge also appears on units in the library. It is created using backgrounds, badges and colours that are contained in bags and crates awarded at the end of a match. The type of bag or crate, common, uncommon, rare and epic, is dependent on how well you did in the game. You will find these bags and crates in the Market tab at the top of the main lobby page as shown in the below pic.
You have the option to Open, Exchange for in game currency or Sell for cash in the Steam community marketplace. When you open the bags or crates, their contents are revealed. The steps below show you how to create the squad logo.

Firstly click on either the squad badge (shown in yellow box below) or your steam avatar (shown in blue box below) found directly above the chat box in the main lobby. You will note that my squad badge is a German Cross shown on the right.

This opens up the Call to Arms Profile Screen. It is here that you can select Badges, Backgrounds, Clan Tag and in game HUD Colour. The Pics below reveal what is found under each sub heading.

• Badges.

You acquire badges from the bags, crates and boxes that are sometimes awarded after you complete a game. Depending on how well you performed in game will determine the class of box you are awarded. The German Cross you see is an epic item that I received when I opened an epic box that I was awarded. Simply click on one of the badges you have been awarded and it will become the badge for your in game profile.

• Colour

Sometimes spray paint cans are found inside bags and crates when you click on them. The colour spray can you earn appears as a colour in the field highlighted above in yellow. This is where you select the colour of your badge or background.

• Background

Simply select a background image and a colour. This will be your background for your chosen badge and will appear on your vehicles in game or in library.
- Remember to save by hitting the floppy disk icon at the top right of the above pic.
You have now created your Squad emblem to appear on your vehicles in game. The emblem is seen by other players in game.

• Clan Tag

You will note that I have the word MAPS preceding my name in the player list shown to the right of the first picture in this guide. This is the clan tag. The below image shows where it is located in the profile box. Simply type the letters in the field and they will show next to your name.

The Clan Tag is limited to 4 characters and can be any colour that you have in your market place inventory. It will only appear in the player list in the main lobby.

• HUD

The HUD is the screen that appears when you are in First Person mode in game. The area in yellow below is where you can select the colour of your HUD. You can only select colours that are in your inventory that you have been awarded when opening bags and crates.

That concludes the guide on Squad Badges, Clan Tags and HUD colours.