Sentiment Analysis Using Neural Networks with Python
Here's how to create such a network. Convert your text into numbers using some tokenizer (Tensorflow's Keras has one). Break it off into equal blocks of some size x. Feed these blocks into an Embedding layer followed by LSTM or GRU (or their bi-directional variants) and finally have a three way classification (positive, neutral or negative) or for regression just a single sigmoid.
One trick though if you have class imbalance, train with full data in the beginning (some initial epochs). Then, for the further iterations, drop the neutral data, just train on positive and negative examples (since, you mostly have a lot of neutral data in these cases).