About Process model

Here is a couple of process modeling courses from Appian academy.

academy.appian.com/
academy.appian.com/
https://academy.appian.com/#/online-courses/278aded9-db23-4a78-84a9-74d0b550d05b

Here is the documentation for process modeling.

https://docs.appian.com/suite/help/21.1/Process_Modeling_Tutorial.html

Hope these resources will be helpful for you.

Hi, 

Nothing to worry, Just run through the Tutorials from Appian Academy (the tutorial will teach u just how to create a PM and about the nodes used). Also to understand it better , please go through any of the Process models from your project's Application which has a smaller flow in it first (that u find it easy or less complicated) .

1. First open the variables tab & analyse what have been mapped (u can see few of the CDTS or their own variables) - this is the first step that developers do.
2. Open each & every nodes used one by one and their respective configured Inputs & Outputs. 
you will be able to see rules/variables mapped in it 

3. just open those expression rules in ur designer application and understand the purpose of them used/created

4. you can understand  the PM completely only if u go by analysing every nodes and their purposes. 

5. you can even ask someone whom you know is proficient /senior to transfer u a basic knowledge on it so as to help yourselves to be a little confident enough

Its okay. https://docs.appian.com/suite/help/21.1/process-model-object.html you can refer to this documentation link, in this link everything is explained properly. You can also configure each node one by one and understand use of it so it will be easy to understand.