Take a look at this guide. You're looking at endurance training with what you want to do. If you want to put on mass, there's no way to get around lifting some heavy (for you) weight.
B. Mostly Myofibral and Sarcomere Hypertrophy and very little Sarcoplasmic Hypertrophy occur with rep ranges of 3-5.
(Sarcomere hypertrophy increases contractile proteins in muscle thereby increasing strength directly and also size.
Book knowledge suggests that growth here will be mostly myofibral/ sarcomere hypertrophy and will be accompanied with strength gains in other rep ranges and improvements in neural efficiency. Therefore this is perhaps the best rep range for increasing strength. Better balance of load / work done for hypertrophy so no surprises there.)
C. Myofibral, Sarcomere, and Sarcoplasmic Hypertrophy (lots of growth as well strength gain within this rep range with little transfer to 1rm) occur with rep ranges of 5-10.
(Sarcoplasmic Hypertrophy does not directly increase strength but can affect it by increasing tendon angle at the attachment - but of course it increases size.)
D. Some Sarcoplasmic with little Myofibral and Sarcomere Hypertrophy occur in rep ranges of 10-15. (More fatigue and a greater extent of waste products are associated with this rep range.
Possible increase in capillary density.)
E. Capillary density increases with little Sarcoplasmic growth with rep ranges above 15. (Muscle endurace begins to become a factor (but who needs that?).
Also, waste products are intense – lactic acid buildup to the point of making some individuals sick.