How you can know you are going to Heaven  

You can be saved and know it!! God says in I John 5:13 "These things have I written unto you that believe on the name of the Son of God: that ye may know that ye have eternal life..." 

You must realize that you have broken God's law and that makes you a sinner.
Romans 3:23 "For all have sinned and come short of the glory of God." 

You must realize that there is a penalty for your sin. Romans 6:23 "For the wages of sin is death..." Luke 16:23 "And in hell he lifted up his eyes being in torments..." 

You must realize that Jesus shed his blood and died for your sins. Romans 5:8-9 "But God commendeth is love toward us, in that, while we were yet sinners, Christ died for us. Much more then, being now justified by his blood, we shall be saved from wrath through him. "

You must repent of your sin and receive Jesus as your Lord and Savior.
Romans 10:13 "For whosoever (that includes you) shall call upon the name of the Lord shall be saved." 

Jesus is the only one who is able to save you. Hebrews 7:25 "Wherefore he (Jesus) is able also to save them to the uttermost that come unto God by him, seeing he ever liveth to make intercession for them. "

Today is the day of salvation. II Corinthians 6:2 "... behold, now is the accepted time; behold now is the day of salvation." If God is speaking to you, now is the time to be saved."