Bitcoin Forum

How to start a website like Bitcointalk.org? what is the skill or requirments needed? do we need to start like small company or hire skilled people like Information technology students? what should I things to be known before I start everything.

Just for creating a website (a forum in your case) like bitcointalk.org,
You'll just need hosting and a script.
That's all.

But with larger user base, problems too increases.

Well, bitcointalk is a forum. You need to know programming languages to make website, to know how hosting works and all that related stuff. Also, very important is security. Bitcointalk was attacked many times in the past and there's often this risk. If you wanna to make a large user base website you need to take care of users' security and privacy. No leak of information is allowed.
If you are not so savvy about that, you better hire experienced stuff. You don't need to start a company to run a website btw...

There are many free forum packages out there, and most are patched regularly to keep up with security.

The issue will be attracting users. 

Contests, bounties, pay per post works for a while, but once you stop the programs the people stop coming.

You need a unique forum to attract people.

I see it a similar.
There are many packages out there, but they are not successfull.
You need to give the people a certain extra, and for that you will have to modify the package.
That would require programmming skills. JavaScript, html, php and sql for the database.
To learn all of them until you are really capable of altering the source code, it will take some time.

Can confirm by experience. The creation of the forum itself is like only 5% of the work you're gonna have to do. I underestimated the advertising/recruiting process, and you gotta have quite a good budget to get a decent start. No competitions with BTC reward, signature campaigns or bounties? Well good luck mate. Your forum will most likely be dead by it's first day.

Like it or not, most people look at bitcoin as a money making method/scheme. So you pretty much need to cater to their wants.

Just buy a domain and hosting on one of the several providers that accept Bitcoin (such as namecheap for example) and download SMF on it.

As for users, it will have to be on a new topic.  What you have to clarify is how you mean this site would be similar to Bitcointalk. If you're aiming to start a Bitcoin forum, you may as well not bother - Bitcointalk is by far the biggest and there are already other places that people go (r/btc, r/bitcoin, Bitcoin Garden, bitcoin.com).

If you're aiming to start a forum on a new topic, it's really about the forum's relevance to the users.  The forum needs to be on a topic that requires a large amount of discussion and is suitable for a forum rather than social media, but isn't already taken by larger forums that are more appealing to their users.

I'm curious to know, who originally started Bitcointalk? Was it Satoshi Nakamoro himself?

Forums are one of the hardest types of websites to run, maintain and monetize.

You are better off creating a simple blog and adding quality content. You can earn revenue for displaying ads on your blog from ad networks like http://coinhits.com

Blogs tend to rank better on search engines too. It takes a long time to build a successful forum and attract long-term users who post regularly.

This forum is using software that is available for download here https://download.simplemachines.org/ (you have the link in the footer). However, once the number of users goes up, it takes more time/money/resources to handle it. It also takes time to become functional/important resource on the internet. This does not just happen over night. Just check the internet how many forums which are covering BTC topic already exist.