What have you tried so far?
Minus the graphics, can you make that slope there with collisions?
One way often used is to use multiple sprites to define the slope. So say you have a circle sprite you could place them in a row on the grass level. More advanced ideas would be to stretch a rectangle sprite from circle to circle to make the surface smoother.
Anyway, to make the slope continue you just add sprites to the right of the last sprite.
In the simplest case you can do this:
compare: x < screenleft
--- set y to 100*sin(x)+320
--- create sprite at x,y
--- add 32 to x
The "set y" expression is how your slope is defined, and you can do anything with it. Some examples:
100*sin(x)+320 is just a sine wave
100*sin(x)+50*sin(x*3+22)+320 is two sine wave combined to make a varied slope.
(noisejs.perlin2(x*0.44, 0.5)+1)*100+320 uses the noise plugin to use perlin noise.