Update README.md

Author: coder13

README.md

@@ -1,3 +1,47 @@
-Jut some simple lexical analysis and building an Abstract Syntax Tree to evaluate simple mathematical expresssions
+# Calculator
 
-Currently handles PEMDAS, functions, and understanding parentheses back to back as multiplication
+This was done for my CS 480 class.
+
+This does simple lexical analysis and building an Abstract Syntax Tree to evaluate simple mathematical expresssions
+
+It currently handles PEMDAS, functions, and understanding parentheses back to back as multiplication
+
+## Requirements
+
+This requires [NodeJS](https://nodejs.org/en/) and npm.
+
+## Installing
+
+Clone the repository.
+
+```bash
+npm install
+```
+
+## Building
+
+```bash
+npm run build
+```
+
+This will build the typescript code into executable NodeJS.
+
+## Usage
+
+Once built, you can run it with:
+
+```bash
+./bin/calc <expression>
+```
+
+The entire expression must be the first argument so if you want to add spaces, you must use quotes.
+
+Parantheses and other special characters confuse the shell so you will need to escape them with `\` or use quotes.
+
+## Tests
+
+Test can be ran with:
+
+```bash
+npm run test
+```