Where I can obtain a working visa in Bangkok and how and how much..?

If you mean a "visa to allow your working" in Thailand, the process is not as easy as one would think.
Legally working in Thailand requires a Work Permit and a visa that matches, i.e. work in Thailand visa.
Start with your employer who should help you get the Work Permit and the visa; get advice there first and hope you will get concrete help because the employer's part of the work permit process involves them certifying that you have the unique skills that justify them hiring you (instead of a Thai citizen) and company documents. That makes up a pile of papers only your employer can provide. I hope your employer goes with you to Labor Dept in BKK; maybe they will give you the documents to take by yourself but language will be a problem, likely. There is a fee and a delay of one to two weeks.

For the thing often called "a work visa," you must get from your employer proper documents that you take to any Thailand embassy to apply. Note that there are no Thailand embassies inside Thailand. Usually YOU pay for the travel and the fees, but you must have documents from your employer to show. There is a fee and turn around time usually overnight. YOU pay hotel, too, unless have a generous employer.

Note the difficulty if you are trying to start your own biz (with a Thai partner) because then you have to provide your own documents. That will mean hiring a lawyer, likely.

If you are legally employed here, your employer will help with the process. In my case, my employer takes care of literally every part of the process. I only have to show up in the business office at work to sign a paper once in a while. Get a job first, then come over.