Visit a dentist and get your teeth and tissues completely evaluated.Once the treatment is planned and executed,follow the maintainence protocol strictly.You should do just fine.
you need to visit a dentist and get a check up done. get a good scaling and polishing done. maintain proper brushing technique. brush twice daily, floss regularly, rinse after every meal.also, if there is a cavity, you can get it filled by the dentist.
You wrote that your "Teeth are in bad condition". The reason for it can be in correct brushing method, the brush you are using is not good (bristle of brush are very hard) as none of us visit a dentist to know proper brushing method and one should brush his teeth twice. Proper care should be taken by rinsing aftet every meal and use of other method like floss and inter dental brushes.
The next step for you should be :-
1.learn proper brushing method and which brush should one use (extra soft bristle brush)
2. Get ur teeth cleaning (scaling) done .
3.If there are cavities/caries kindly get them filled .
4. If other oral problems persist kindly follow ur dentist instruction and get them treated
Appreciate that u r taking care of ur health.brush properly and use floss.refer YouTube to understand how-to brush correctly and use of floss.get dental checkup and cleaning twice a year.Regards Dr Ratnika Agarwal ,Smile Up Dental care & implant center