Going to the Chapel of Love

The Dixie Cups are an American pop music girl group of the 1960s. They are best known for their 1964 million selling disc, "Chapel of Love".  "Chapel of Love" sold over one  million copies, and was awarded a gold disc.
Gonna is a very informal way to replace going to in  going to (+verb). So Gonna get married = going to get married.   "Say I do" is a popular way to say get married.

CHORUS:

Goin' to the chapel and we're 

Gonna get married 

Goin' to the chapel and we're 

Gonna get married 

Gee, I really love you and we're 

Gonna get married 

Goin' to the chapel of love

Spring is here 

The sky is blue 

(whoa-whoa-whoa) 

Birds all sing 

As if they knew 

Today's the day 

We'll say I do 

And we'll never be lonely anymore 

Because we're

CHORUS

Bells will ring 

The sun will shine 

(whoa-whoa-whoa) 

I'll be his and 

He'll be mine 

We'll love until 

The end of time 

And we'll never be lonely anymore 

Because we're

CHORUS