If you could please help me out with this that would be awesome!

There are several answers possible  ......

Using the form  y  =  A sin ( Bx + C)  + D

The period of the graph  is 15 units in length.....then each quarter point  = 15/4 units

The amplitude of the graph = A  =  4

The midline of the graph is y = 1   = D

We can solve for B  thusly

pi/2 =  (15/4)B

pi/ 2  * (4/15)  = B

(2/15)pi  = B

And  we can find C thusly......note that we are shifting the normal cosine curve to the right

1   =  sin [ (2/15)pi (15/4) - C] + 1       subtract 1 from both sides

0  =  sin  [ ( pi/2)  -  C ]     →  cC  = pi /2 

So....our function is

y  = 4  sin [ (2/15)pi* x - pi/2 ]  + 1

Here's the graph :   https://www.desmos.com/calculator/gdqmefwhyc