Update README with instructions

README.md

 # dgraph
 Distributed Graph Serving System
 
+# Installation
+DGraph depends on [RocksDB](https://github.com/facebook/rocksdb).
+So, install that first.
+
+```
+# First install dependencies.
+# For Ubuntu, follow the ones below. For others, refer to INSTALL file in rocksdb.
+$ sudo apt-get install libgflags-dev libsnappy-dev zlib1g-dev libbz2-dev
+$ git clone https://github.com/facebook/rocksdb.git
+$ cd rocksdb
+$ git checkout v4.1
+$ make shared_lib
+$ sudo make install
+```
+
+This would install RocksDB library in /usr/local/lib. Make sure that your `LD_LIBRARY_PATH` is correctly pointing to it.
+
+```
+# In ~/.bashrc
+export LD_LIBRARY_PATH="/usr/local/lib"
+```
+
+Now get [dgraph](https://github.com/dgraph-io/dgraph) code:
+```
+go get -v github.com/dgraph-io/dgraph/...
+```
+
+# Usage
+
+## Data Loading
+Let's load up data first. If you have RDF data, you can use that.
+Or, there's [Freebase film rdf data here](https://github.com/dgraph-io/benchmarks).
+
+To use the above mentioned Film RDF data, install [Git LFS first](https://git-lfs.github.com/). I've found the Linux download to be the easiest way to install.
+Once installed, clone the repository:
+```
+$ git clone https://github.com/dgraph-io/benchmarks.git
+```
+
+To load the data in bulk, use the data loader binary in dgraph/server/loader.
+Loader needs 2 directories:
+- mutations, where mutation commit logs are stored and
+- postings, where posting lists are stored.
+
+```
+$ cd $GOPATH/src/github.com/dgraph-io/dgraph/server/loader
+$ go build . && ./loader --rdfgzips=path_of_benchmarks_dir/data/rdf-films.gz,path_of_benchmarks_dir/data/names.gz --mutations DIRPATH/m --postings DIRPATH/p
+```
+
+## Querying
+Once data is loaded, point the dgraph server to the postings and mutations directory.
+```
+$ cd $GOPATH/src/github.com/dgraph-io/dgraph/server
+$ go build .
+$ ./server --mutations DIRPATH/m --postings DIRPATH/p
+```
+
+This would now run dgraph server at port 8080. If you want to run it at some other port, you can change that with the `--port` flag.
+
+Now you can run GraphQL queries over freebase film data like so:
+```
+curl localhost:8080/query -XPOST -d '{
+me(_xid_: m.06pj8) {
+        type.object.name.en
+        film.director.film {
+                type.object.name.en
+                film.film.starring {
+                        film.performance.actor {
+                                film.director.film {
+                                        type.object.name.en
+                                }
+                                type.object.name.en
+                        }
+                }
+                film.film.initial_release_date
+                film.film.country
+                film.film.genre {
+                        type.object.name.en
+                }
+        }
+}
+}' > output.json
+```
+This query would find all movies directed by Steven Spielberg, their names, initial release dates, countries, genres, and the cast of these movies, i.e. characteres and actors playing those characters; and all the movies directed by these actors, if any.
+
+The support for GraphQL is very limited right now. In particular, mutations, fragments etc. via GraphQL aren't supported. You can conveniently browse [Freebase film schema here](http://www.freebase.com/film/film?schema=&lang=en). There're also some pointers in dgraph-io/benchmarks/data/README.md.