more basics

docs/src/manual/basics.md

@@ -1,3 +1,29 @@
 # Basic Usage
 
-*Charging Ion Capacitors*
+## Installation
+
+```julia
+Pkg.clone("https://github.com/MikeInnes/DataFlow.jl")
+Pkg.clone("https://github.com/MikeInnes/Flux.jl")
+```
+
+## The Model
+
+*Charging Ion Capacitors...*
+
+The core concept in Flux is that of the *model*. A model is simply a function with parameters. In Julia, we might define the following function:
+
+```julia
+W = randn(3,5)
+b = randn(3)
+affine(x) = W*x + b
+
+x1 = randn(5)
+affine(x1)
+> 3-element Array{Float64,1}:
+   -0.0215644
+   -4.07343  
+    0.312591
+```
+
+## An MNIST Example