If you are having trouble in Chemistry then did you speak with your teacher, counselor or school's admin. office to see if they have any tutoring support or resources?
They may have tutors, study groups, instructional materials, educational software and etc. that will help you learn and understand the subject a lot better?
You can use the search engine Google.com to find many free tutorials, forums and other information
Tutoring?some of these tutors or websites are free
Chemistry tutoring
http://www.google.com/search?hl=en&source=hp&q=Chemistry+tutoring&aq=f&aqi=g10&oq=There are many online forums for many subjects?you can ask them for any advice and information
Chemistry forum
http://www.google.com/search?hl=en&source=hp&q=Chemistry+forum&aq=f&aqi=g1g-s1g2g-m6&aql=&oq=&gs_rfai=CrjdxZ3qLTP7BGI6EygSBj9D8BAAAAKoEBU_Q6Z6aThere are answer engines such as
www.wolframalpha.com that will solve almost any math or science problem and has information for almost any subject or topic
Chemistry
http://www.wolframalpha.com/input/?i=ChemistryThere are many free tutorials and information to choose from
Chemistry tutorial
http://www.google.com/search?hl=en&nfpr=1&ei=-NJ_S7akB4j18QaQupCYBQ&sa=X&oi=spell_nofullpage&resnum=0&ct=result&cd=1&ved=0CAUQBSgA&q=Chemistry+tutorial&spell=1Dmoz.org has many tutorials for Chemistry and other subjects
http://www.dmoz.org/Science/Chemistry/SparkNotes has good study guides for various subjects and resources for preparing for various tests
Chemistry
http://www.sparknotes.com/chemistry/You can go to your local library or store or an online store like Amazon.com to find many good books, DVDs, science kits and etc. for learning many things
Chemistry
http://www.amazon.com/s/ref=nb_sb_noss?url=node%3D21&field-keywords=ChemistryYouTube has videos for learning almost any subject or topic
stoichiometry
http://www.youtube.com/results?search_query=stoichiometry&aq=fKhanacademy has many free tutorials for various subjects on YouTube
http://www.khanacademy.org/I hope this helps!