I am not 100% what you are trying to say in your post. But, what I think you are trying to ask is how you get new weapons and how to buy them? Hopefully I'm interpreting that correct, so here is your answer:
1- When you are on the main menu screen for Argo, you will see the button Equipment, you are going to click on that
2- After you load into Equipment, you will see Skill Tree at the top, the third button when going from left to right.
3- When you are viewing the Skill Tree you will see in the upper right your skill points (represented by the Argo Logo) and your Argo Currency (represented by an AC, I believe)
4- In the Skill Tree, you will use your skill points to unlock access to new weapons and equipment. When you Unlock something in a certain row, you will then be able to use skill points on the attachments in that corresponding row. ex: Assault Rifles II will unlock Sights II
5- After you use your Skill points, you will then go to your Armory, which is the second and middle button at the top of your screen.
6- In the Armory is where you will use your Argo Currency to purchase new weapons and attachments for those weapons; or new equipment such as grenades.
7- After buying whatever your heart desires, (And whatever you have unlocked) go to the first tab at the top of your screen.
8- Here is where you will make your classes and equip your new gear. Pretty self-explanatory how to do this.
I really hope this is what you were asking. :)