Hii,
I am new to architectural designing of the applications, and our company is not following any procedures and we are not documenting any thing regarding the software development. So can anybody help me to understand regarding the above context. If you find any useful articles links please forward me.
Find a good UML tool (can't recommend any), a good relational model designer (SQL Power Architect fits the bill well) and document your use cases, initial class and relational models. Use the other models on an as-needed basis. Use a simple tool to draw UI mock-ups (e.g. Pencil). Make sure this content is safe, accessable by all team members, versioned and, if possible, indexed.
As you design the individual components, think about where you will concentrate complexity, document what the complex parts, how you plan to test them and the scope of your tests.
During implementation, keep your implementation documentation structured: issue tracker for tasks and version control commit messages to know what's going into the codebase. When you release software, use the commit history and the tracker to document release changes.
The above should get you started: you'll have your own ideas about the next steps to take.