analyse project requirements for offering jobs and recruitment

This is a very open ended question and one that goes beyond the scope of the voluntary effort provided on these forums. You might find someone willing to chip in their time for no compensation however, I recommend you open a GIG for this

This will give you an idea of what technologies bayt is using.  If you want to do what they are doing, these are the areas of technology expertise  you will need to develop or hire.  I would recommend using an advertising agency with web expertise.  It's a big project.

I would also recommend skipping Yii and using Laravel instead.  I'm sure their choice of Yii was made years ago.  It's not the choice anyone would make today.

https://builtwith.com/?https%3a%2f%2fwww.bayt.com%2f

I suppose it goes without saying, but I'll say it anyway.  The success of a web site like this one is not so much a matter of putting up the web application.  It's a matter of getting people to actually use the site so it becomes an online community.  For purposes of business planning you may want to learn about Metcalfe's Law.  It will work for you as you are growing and will work against you if the community ever starts to decline!  You will want to plan carefully about how you will target and acquire clients -- what value proposition you will produce that will make the clients come to your site instead of any other site.

Thank you so much Ray Paseur,but why usign Laravel instead  of Yii Framwork?

A good starting point for projects like this is to consider cost of ongoing maintenance + enhancements + fixing performance issues.

Using LAMP + WordPress as your starting point will provide you with a product where all the above will tend to be cheaper than custom code.

Going the custom code route, keep in mind only your original developer(s) will truly understand code written.

You'll have to pay these people forever or each time you require code changes, your newly hired developers will have to learn your custom code  base.

WordPress can be tooled to be extremely fast (5K-10K reqs/sec for logged in users) + handle 1000s of simultaneously logged in users...

If the underlying LAMP Stack is tuned correctly.

Since LAMP Savants are rare as purple lemmings, WordPress speed problems tend to primarily relate first to poor LAMP tuning.

From a business perspective, I tell my clients to pick WordPress over custom code to reduce long term costs.

I run a private, high speed hosting company + I can saw from experience that clients I take on with custom code bases tend to sleep poorly + deal with numerous oddball problems WordPress projects never experience.

Be sure you consider well your costs over entire project life cycle before choosing your platform technology.

My suggestion to clients is just to do a 180 + run anytime some developer pitches them a custom code solution... as custom code is great for developers billing for work + horrible for site owners paying for work.

I am a developer who is going to realize site, I just want a little help, they give me your opinion on what framework used, what to start, by what stage I can begin ...

This article pretty much sums up my opinions and experience with PHP frameworks.
https://www.sitepoint.com/the-state-of-php-mvc-frameworks-in-2017/