I need guide to buy a bike?

You can find a guide at your local bike shop. He will ask you what kind of riding you plan to do and will suggest several different models for you to try out.

I see...................................

Visit your local specialist bike shop and talk with them about your budget and your cycling experience and future needs. Try, try, try before you buy.

Don't. They are a menace to pedestrians and other road users.

I'll assume you're referring to a bicycle & not a motorcycle.  

1) Determine "Where & How" you'll be riding.  What do you NEED the bike to do for you.  Will you be riding strictly on paved surfaces?  All off road?  Or, a little of both?  

2) If you need it to last, do NOT shop at a big box store or Amazon.  A) Big box store bikes are haphazardly assembled by clueless minimum wage "associates".  Most aren't even safe to ride out of the store.  B) Amazon bikes need to be assembled & tuned-up.  That's right...all bikes straight out of the box need some adjustments made.  Are you a professional bike mechanic?  If you pay a bike shop mechanic to do it right...there went all you the money you (supposedly) saved.  

3) It's so damn simple.  Five words...  Go To A Bicycle Shop!  A) Better quality sold & serviced by professionals.  B) Service after the sale!  All new bikes come with a FREE service warranty.  Big box stores do NOT service what they sell.  C) Test rides are FREE!  Yes...you might have to leave collateral, such as a drivers license or credit card.  But, you'll get it back.  D) The money stays in the community.  You're supporting a local business & not some multi-billion dollar corporation.      .      

Get the electric bike 

From Costco